Methods of making tobacco web material



A 1964 F. H. OSBORNE ETAL 3,145,717

METBODOF' MAKING TOBACCO WEB MATERIAL Filed Oct. 22, 12155.?)

TOBACCO /0 EXTRA CT/A/G W/TH WA TEP /2. SEFARATNG WE coA/cEA/rPAT/Ns ANDEXTRACT FROM ,NSOLUBLES ACID/FY/NG EXTRACT l 32 l l /4 l SEPARAT/NG lfif g g PREc/P/TA TE l l 6 I I .SEPAPA TING NEUTRAL/Z/NG THE PULP I THEEXTRACT i i 4 l L, REF/N/NG PULP I ADD/N6 DYE AND 36 AND Ava/Ive FILLERHUMEGTA/VT T0 EXTRACT ADD/N/G K/ a8 REF/N 6 sAruPAn/va WEB CA T/oN/cWITH MODIFIED AGE/VT 22 EXTRACT AND I OH Y/NG FORM/N6 WEB ON &

PAPER MA KING I 40 MACH/NE AND 1 35 DRYING I TPEA Tl/VG WEB 1 i WITH WAX53375 /v u AL 22.5? JATURAT/NG WEB WITH s oLur/olv 0/-' l 42 LINK I GAGENT AND ALDEHYDE CALENDER/NG THEN DR Y/NG 0R EMBOSS/NG mmvrons FAY H.OSBORNE BY WA RREN d. BODENDORF ATTORNEYS United States Patent 3,145,717METHODS OF MAKING TOBACCO WEB MATERIAL Fay H. Osborne, Windsor Locks,Conn., and Warren J. Bodendorf, Montgomery, Mass., assignors to C. H.Dexter & Sons, Inc., Windsor Locks, Conn., a corporation of ConnecticutFiled Oct. 22, 1959, Ser- No. 847,952 15 Claims. (Cl. 131-140) Thepresent invention relates to a new and improved tobacco web material andto a novel method of making same. A principal use of the tobacco Webmaterial of the present invention, although the invention is not limitedthereto, is for forming tobacco webs for use as wrappers for cigars andcigarettes and for use as cigarette fillers.

Heretofore, the wrappers normally used for cigars have been naturaltobacco leaf and the wrappers for cigarettes have been paper. In bothcases, there are many adverse qualities in the wrapping material. Thepaper used for cigarette wrappers not only gives undesirable taste andodor, but in addition the products of combustion from the paper havebeen claimed to be the cause of harmful effects, such as lung cancer.The natural tobacco leaf used for cigar wrappers is generally of themost expensive grade and is diflicult to use economically because theleaves are limited in size, are brittle and difficult to handle, andrequire a very large proportion of hand labor during manufacture of thecigars. In addition, there is no control as to the rate of burn, type ofash, undesirable constituents and strength, since the tobacco leaves areused as found in nature and there is no practical way to modify thecharacteristics mentioned.

Many attempts have been made heretofore to produce continuous webs oftobacco by the use of various techniques and methods, but in general,such atempts have met with only limited commercial success and so far asis known, none of these prior methods has been successful in providing atobacco web material suitable as an outer wrapper for cigars, althoughin some instances such web materials have been used as a binder. Ingeneral, the web materials of the prior art have been of relativelythick structure, undesirable in taste, aroma and appear ance, and oflimited strength. In addition, such Web materials have been relativelyexpensive to produce, principally due to the slow production methodsemployed.

More recently it has been discovered that the incorporation of activatedalumina in a tobacco sheet for use in cigarettes has the highlydesirable effect of reducing the temperature of burning and thevolatilization of alkaloids and suspected carcinogens.

The aim of the present invention is to provide a tobacco web materialhaving the desirable characteristics of natural tobacco leaf but withmany added advantages such as improved taste, strength, uniformity,burning characteristics, aroma, etc., and to produce this Web incontinuous lengths of desired width and thickness at relatively low costso that the web may be used economically as a substitute for naturaltobacco leaf, and, in brief, provide a better product than naturaltobacco leaf at a lower cost to the eventual consumer. A further aim isto provide a novel method for manufacturing self-supporting tobacco webcontaining substantial amounts of activated alumina.

In general, the method of the present invention for forming a continuousweb of tobacco comprises the steps of separating the water-solublematerial from the insoluble portion of the tobacco, forming a Web fromthe insoluble portion and then re-uniting the soluble portion with theinsoluble portion in the final web. Certain novel steps in the treatmentof the soluble and insoluble portions of the tobacco enable theprovision of a tobacco web 3,145,717 Patented Aug. 25, 1964 havinghighly desirable characteristics, as will be fully describedhereinafter. The insoluble material is formed into a web by the use ofspecial techniques on paperm'ak ing machinery and thus can be made inwide widths and in any desired length at relatively low cost. The webhas a desirable appearance and is improved in taste, aroma and burningcharacteristics when compared with natural tobacco leaf. The final webmaterial may be formed in any desired thickness and length rendering itsuitable for use as a wrapper for cigarettes and cigars as Well as abinder material; and because of its characteristics, automatic machinerymay be employed to form the web into binders or wrappers for cigars andcigarettes, thus eliminating much hand labor.

The invention will be described in detail in connection with theaccompanying drawing in which the single figure is a schematic anddiagrammatic showing of a preferred method of carrying out theinvention.

Referring to the attached drawing, the tobacco feed for the process maybe Whole leaves, broken leaves, cuttings, stemmings and variousfragments or waste. For high grade cigar Wrappers, only high gradetobacco leaves, or cuttings and stemmings from these leaves, are used.For cheaper cigar wrappers or for binders, lesser grade leaves andfragments may be used. If so desired, the tobacco may be shredded or cutinto smaller particles which, however, is not necessary for the practiceof the present invention.

The tobacco is first subjected to a water extraction operation,designated by the numeral 10, wherein the tobacco is treated to separatethe water-soluble constituents. This is most conveniently accomplishedin a closed tank at elevated temperature, and minor quantities ofchemical agents such as potassium carbonate may be added. The water usedfor the extraction is preferably pure, and deionized water may be usedto advantage. Preferably only 1 to 3 parts of water per part tobacco areutilized to minimize the handling requirements for the subsequentevaporation, and extraction in a closed tank at about F. for one to twohours will be normally sufficient.

In the next step, designated generally by the numeral 12, thewater-soluble constituents of the tobacco or extract are separated fromthe insoluble portion by any convenient process, such as draining,pressing and/or centrifuging. It is contemplated that the separatedportions will normally be used immediately and thus no precautions arerequired. However, if the extract is not to be used soon afterextraction, refrigeration is required to prevent the formation of moldwhich would render the extract unusable. Similarly, if the insolubleportion is not to be used immediately, it should either be dried such asby forming a dry pulp lap or, if it remains wet, it should be storedunder refrigeration.

The insoluble portion of the tobacco is then subjected to chemicaldigestion, indicated generally by the numeral 14, to form a fibrouspulp. This treatment may be a caustic digestion utilizing 1 to 10percent by weight of caustic (calculated as NaOH), and preferably 4 to 5percent. It is most desirably carried out in a pressure tank at about 20to 40 pounds per square inch pressure, and preferably about 30 pounds.Generally, treatment at these pressures for two to four hours will besufiicient. As a specific example, treatment with 5 percent by weight ofcaustic for about three hours at 30 pounds per square inch pressureproduces highly desirable results.

Alternatively, the digestion step may utilize nitric acid in an amountequal to about 15 to 40 percent by weight of the tobacco insolubles andpreferably about 25 to 30 percent. The time for the treatment will varywith the temperature employed, but about three hours at 60 C. willnormally be sufiicient. As will be readily apparent to those skilled inthe art, this treatment requires special corrosion-resistant equipment,but has the advantage of operation at atmospheric pressure and lesserconsumption of digesting agent. A further advantage is that the tobaccopulp produced is found to have a light, highly desirable tobacco color,thus eliminating any requirement for bleaching which might otherwisearise. As a specific example, treatment with 4 parts of 7 percent nitricacid per part tobacco insolubles (about 28 percent by weight HNO at 60C. for three hours is quite satisfactory.

The digestion treatment produces a fibrous pulpy mass which is thenseparated from the digestion liquor in a step generally indicated by thenumeral 16. This may conveniently be accomplished by draining andpressing.

The caustic digestion treatment is preferably so controlled by theamount of caustic added that the resultant pulp is neutral. However, thentric acid treatment will produce an acid pulp which is then rinsed withwater, neutralized with agents such as sodium hydroxide or sodiumcarbonate, and rinsed again.

The tobacco pulp is then refined in a beater, as indicated by thenumeral 18. In this step, the tobacco pulp is furnished to a regularpapermaking beater and sufficient Water is added to form a slurrycontaining approximately 1 to 7 pounds of pulp per 100 pounds of water.The tobacco pulp is refined by the beater roll in a brushing operationwhich macerates the fibers of the pulp. This operation will generallyrequire about one-half hour. At this point :a small amount of filler maybe added to improve the ash formation of the final web, and agents suchas titanium dioxide, clay, calcium carbonate, or alumina are desirablyemployed. The amount of filler added can vary over a wide rangedepending upon the end use. For cigar wrappers, the addition of 2 to 8percent by weight of the filler based upon the final product givessatisfactory results, while for cigarette wrappers, additions of up to15 percent produce desirable results.

If so desired, large amounts of activated alumina may be added to thetobacco fibers in the beater to produce a finished web incorporating thealumina for use in cigarettes and the like. Generally, the amount ofactivated alumina added for this purpose may vary to provide from 10to75 percent by weight of the finished sheet, and preferably between 50to 65 percent by weight.

The activated alumina must be of sufiiciently small particle size todisperse in the slurry and blend in the web, and should be of a particlesize less than 200 mesh and preferably less than 325 mesh. Since theactivated alumina added has a tendency to wash out with the waterdraining from the web, it is generally necessary to add an excess ofalumina to the tobacco slurry to obtain the desired percentage in thefinal product. The actual ratio added to the slurry will vary with themachine employed, and the conditions of operation, and can be readilydetermined.

The slurry of tobacco pulp and inorganic material is then treated tofurther refine the tobacco pulp by running the slurry through a Jordanmachine, or disc refiner, or both, as indicated by the numeral 20.

The tobacco fiber slurry thus prepared is formed into a web on apapermaking machine as indicated by the numeral 22. By way of example,there may be used a paper machine of the type shown diagrammatically inthe Play H. Osborne Patent No. 2,045,095, issued June 23, 1936, which isdesigned to run with very low fiber concentration in the headbox.However, other types of paper making machines may be used, such as aconventional Foudrinier machine. The tobacco slurry is admixed withwater in the trough and headbox to provide a consistency ofapproximately 0.5 to 1.0 percent by weight solids. The thickness of theweb may be varied over a Wide range by varying the consistency of theslurry in the headbox.

As indicated by the numeral 24, an aqueous solution of a non-toxiccationic agent is simultaneously fed into the headbox in an amount equalto about 0.5 to 12.0 percent by weight of tobacco fibers, and thiscationic agent will generally constitute about 0.05 to 6.0 percent ofthe finished sheet. In particular, cationic starch has proven highlybeneficial for this purpose. As a specific example, 2 percent by weightcationic starch solution is fed into the headbox in an amount sufficientto provide about 5 pounds of starch per 450 pounds of fibers introduced.The addition of the cationic agent is found to improve the strength anddrainage of the web, as well as act as a fiocculating agent.

Although, in the present invention, digested tobacco fibers alone may beutilized to produce the web, in some instances it is desirable to add tothe web a minor proportion of conventional papermaking fibers for addedstrength as indicated by the numeral 26. Generally, the conventionalpapermaking fibers added may vary from a small amount to a maximum ofabout 2 pounds per 15 pounds of tobacco fibers, and preferably less than1 pound per 15 pounds. The conventional papermaking fibers are added tothe headbox as a dilute slurry wherein they intermingle and admix withthe tobacco fibers to form a composite web on the Fourdrinier wire.

The particular conventional papermaking fibers selected will depend onsuch matters as cost and the amount of strength desired in the finalweb. For maximum strength, it is preferred to use manila hemp fibershaving a fiber element length of 5 to 8 millimeters.

As an alternative to the chemical digestion of the insolubles, a tobaccoweb of lesser grade and quality can be prepared by more extensivemaceration of the insolubles during the refining steps without chemicaldigestion, as indicated by the dotted lines from steps 12 to 18 on theattached drawing. In this embodiment, the refining must be suflicient tocut the insolubles into small particles, and natural fibers must beadmixed with the tobacco fibers in an amount sufficient to provide aslurry containing 5 to 13 percent by weight of natural fibers.

An advantage of the method of the present invention is that by freeingthe tobacco of water-extractable material prior to forming the web, muchgelatinous material, such as pentosans, is removed and the resultingslurry, being of a much less gelatinous nature, will drain suflicientlyrapidly on a conventional Fourdrinier wire screen to permit facileproduction and good uniformity of the web. Due to the low wet strengthof the tobacco web at this point, it is necessary to provide thepapermaking machine with a conventional felt carrier to transfer the webfrom the Fourdrinier Wire to the dryers. Upon completion of drying, theweb may be rolled up as in any other paper making process.

Next, the dried web is preferably treated to improve its wet strengthand other characteristics as indicated by the numeral 28, especially forpreparation of a wrapper sheet. In this step, the web is saturated witha solution of aldehyde and a non-toxic cross-linkable agent selectedfrom the group consisting of protein and polymeric alcohols, to which ahumectant may also be added. The wetstrengthening is accomplished bycross-linkage and insolubilization of the protein or polymeric alcohol,which is preferably accelerated by a mineral catalyst, such asphosphoric acid. A preferred solution for this purpose may haveapproximately the following formula:

Percent by weight Protein or polymeric alcohol 3.0 Aldehyde 1.5Humectant 3.0 Phosphoric acid (86%) 0.1 Water 92.4

The polymeric alcohol, polyvinyl alcohol, is most desirably employed,and the protein utilized may be soybean protein, casein, or any proteinof the collagen type, such as gelatin. The protein or polymeric alcoholis added in an amount sufficient to provide about 2 to 8 percent byweight of aldehyde cross-linked material in the finished web, andpreferably about 3.5 to 4.5 percent. The aldehyde is added in an amountsufficient to crosslink and insolubilize the protein or polymericalcohol, and formaldehyde, acetaldehyde and glyoxal may conveniently beemployed. If so desired, alcohol, such as ethyl or isopropyl alcohol,may be added to the solution to facilitate penetration or wetting of theweb. Saturation may be effected by spraying the solution thereonto or byrunning the web through a bath of the solution. After saturation, theweb is dried on conventional papermaking machinery and rolled up in theusual manner for further processing.

Returning to the filtrate or extract which was separated from theinsoluble portion of the tobacco at step 12, the extract is concentratedby evaporation and acidified as indicated by the numeral 30. Theconcentration may be accomplished by any of the well-known methods, butis preferably conducted with as little agitation as possible and withoutvigorous boiling so as to avoid distilling out the more volatile tasteand flavoring compounds. The extract is preferably concentrated to aspecific gravity of 1.10 to 1.25.

Following concentration, the extract is acidified to a pH of 4 to 6, andpreferably about 5. This acidification is conveniently carried out byuse of a mixture of phosphoric acid and citric or other weak organicacids in a 1:1 to 1:2 ratio. Upon acidification, a precipitate formswhich is comprised mainly of acid-insoluble proteins responsible formuch of the bad taste and aroma when natural tobacco is burned.

If so desired, the extract may be decanted or otherwise separated fromthe precipitate, as indicated by the numeral 32, to obtain a mildertobacco sheet.

After acidification (and separation of the precipitate, if so desired),the extract is neutralized by the addition of potassium carbonate asindicated by the numeral 34. By neutralization, it is meant that the pHshould be adjusted by the addition of potassium carbonate into the rangeof 6.5 to 7.2, and preferably 7.0 or slightly below. In this range, noexcess carbonate ion will be introduced into the solution andsubstantially all that which is introduced will decompose in solution toevolve carbon dioxide. These steps of acidification and neutralizationwill introduce an amount of potassium sufiicient to form organicpotassium salts of the water-soluble constituents of the extract inexcess of the amount of potassium nitrate present, which relationshiphas been found essential to produce good burning properties in the finalproduct. Carbonate ion, if present in the final web in any appreciableamount, would tend to interfere with the burning of the wrapper becauseof the evolution of carbon dioxide. By this modification of the extract,the subsequently impregnated sheet is found to have a uniform, moderaterate of burn, which is most desirable from the standpoint of a goodcigar wrapper.

After neutralization, other desirable additives for the sheet are addedto the modified extract as indicated by the numeral 36. Generally, theseadditives will be humectant and dye. However, other materials may alsobe added to impart, improve or modify other characteristics of the finalweb; and, in particular, 1 to percent polyvinyl alcohol has proven quitebeneficial. A typical preferred formula for the modified extract aftersuch additions is as follows:

Percent by weight The humectant, which may be glycerin, sorbitol orpropylene glycol, is added to impart flexibility to the web, and the dyeis any vegetable coloring for obtaining the 6 desired color in thefinished web. The polyvinyl alcohol not only adds strength to the webbut also functions as a non-tacky humectant.

The base web which had been prepared in the steps previously describedis now treated with the modified tobacco extract as indicated at 38. Theintention here is to put back into the web some or all of the desirablecomponents taken out of the tobacco by the previous extraction; and thismay be after removal of the undesirable components. The web is saturatedwith the tobacco extract in any convenient manner, such as by sprayingor by running the web through a bath of the extract, and the web is thendried in a conventional manner and rolled up. As a result of thistreatment, the web is rendered strong, flexible and easy to handle.

Following the foregoing treatment, the web is then impregnated with anemulsion of water and Wax as indicated at 40. A preferred water-waxemulsion which may be used for this purpose is a dilute emulsioncontaining approximately 8 percent wax solids, preferably a wax ofvegetable origin. The purpose of this step of the treatment is to givethe final product a wax-like appearance and feel simulating that ofnatural tobacco leaf and a degree of water repellency approximating thatof natural tobacco leaf. Polyvinyl alcohol may also be used for thispurpose because of its non-tacky nature. After the Web has beensaturated by running it through the emulsion, it is dried and rolled upin the usual manner.

The final step in the method is indicated generally at 42 and comprisescalendering and/or embossing the final sheet. The calendering gives theproduct a uniform thickness and brings out the waxy appearance. Theembossing gives the product more stretch and more tobacco leafappearance. If desired, the embossing design can be a tobacco leafdesign having stem and veins to make the product simulate natural leaftobacco.

The final tobacco web should have a thicknes sof 0.0015 to 0.008 inchand preferably less than 0.004 inch. A most desirable tobacco wrapper isone having a thickness of about 0.0020 to 0.0030 inch after calendering.The alumina bearing sheet will generally be between 0.004 and 0.008 inchin thickness.

Some of the extract may be used as a component of the wet-strengtheningsolution in step 28, as indicated by the dotted line between steps 34and 28. The mineral constituents in the extract apparently catalyze thealdehyde cross-linking of the protein or polymeric alcohol.Additionally, the use of the extract in this step provides increasedimpregnation of the sheet due to the sizing effect produced by thewet-strengthening material. Although the extract may constitute theentire aqueous component of the wet-strengthening solution, it ispreferable that it constitute less than about 50 percent by weight ofsolution because of the accelerating effect of the mineral constituentsupon the aldehyde cross-linking. The impregnation of the web with thewater-soluble constituents in the two steps 28 and 38 insures thoroughdistribution throughout the web.

In preparing a tobacco sheet containing alumina, the Web from step 22 isimpregnated With the extract and humectant. Wet strengthening is notessential since the sheet is shredded and employed in the body of thecigarette. Although modification of the extract is not essential forsuch sheet, the controlled rate of burn so provided is found desirable.

As above described, the method is employed to form tobacco web materialof conventional tobacco color. If desired, the two components from theextraction step indicated generally at 14, namely, the soluble and theinsoluble portions, may be given a preliminary bleaching or otherdecolorizing treatment, such as by use of hydrogen peroxidfe, to providelighter shades or to facilitate subsequent dyeing. In fact, decolorizingmay be carried out to a sufficient extent to provide a final web whichis white in color and thus particularly desirable as a wrapper forcigarettes. It has been found that such decolorizing does not have anadverse effect upon the taste or aroma of the final product.

In order that the invention may be fully understood, the following aregiven by way of specific examples; but it will be understood that theinvention is not limited thereto.

Example 1 One thousand pounds of tobacco leaves and stemmings wereextracted with 1000 pounds of water for two hours at 190 F. in a closedextraction tank. No chemicals were added. The insoluble portion wasseparated from the extract by draining and pressing, and then was placedin a digestion tank together with 600 gallons of water and 6 gallons of50 percent by weight caustic solution. The insolubles were digested forthree hours at approximately 260 F. and 30 pounds per square inchpressure, after which the pulpy mass was separated from the digestionliquid by draining.

The pulpy mass was then placed in a conventional paper mill beatertogether with 1000 gallons of water, and refined by brushing forapproximately twenty minutes. During the refining operation, the pulpwas admixed with twenty pounds of titanium dioxide. After the refiningoperation in the beater, the slurry was transferred to a Jordan Machinefor further refining.

The refined slurry of tobacco fiber was then fed into the headbox of aconventional Foudrinier papermaking machine, and a dilute slurry ofmanila hemp fibers was simultaneously introduced in an amount sufiicientto provide 1 pound per 15 pounds tobacco fibers. The consistency of theslurry of the two fibers in the headbox was about 0.27 percent byweight. Also introduced into the headbox was a 2 percent aqueoussolution of cationic starch at a rate of about 5 cc. per minute, orabout 5 pounds per 450 pounds of tobacco fiber.

A dry web of about 16 pound weight (24" x 36"480 sheets) was thusproduced, which was passed through an aqueous solution containing 3.6percent by weight polyvinyl alcohol (completely hydrolyzed), 3.6 percentglyoxa1, 0.1 percent phosphoric acid (86 percent), and 3.6 percentsorbitol, and then dried, the web now weighing about 17 pounds.

The extract of water-soluble tobacco constituents from the extractionstep was evaporated to a specific gravity of about 1.20 and equalledabout 240 pounds. The concentrated extract was acidified by addition of/2 pound of citric acid and pound phosphoric acid to a pH of about 5.0.After acidification, the extract was neutralized by the addition of 3.5pounds of potassium carbonate to a pH of about 6 .9. To the neutralizedextract were added 1 pound of vegetable dye, 35 pounds sorbitol and 5pounds of polyvinyl alcohol.

The web was then impregnated thoroughly with the modified extract anddried. Next, the web was run through a Water-wax emulsion containingabout 8 percent solids and dried, after which the web was embossed witha tobacco leaf design suitable for a cigar wrapper.

Upon testing, the finished web was found to have a basis weight of 23.7pounds (24" x 36"480 sheets) and to be 0.0024 inch in thickness. Adensometer test indicated the porosity to be 686 seconds per 400 cc.air. The dry tensile strength (average) was 2344 grams per inch and thewet tensile strength (average) was 344 grams per inch.

Example 2 Tobacco leaves were extracted, digested and refined accordingto the procedure set forth in Example 1.

The slurry containing the tobacco fibers and filler was diluted withwater to provide a headbox concentration of 0.25 percent by weight, anda 2 percent cationic starch solution was simultaneously added. Nonatural fibers were introduced into the headbox.

A web of about 16 pound basis weight was formed from the tobacco fibersand was then impregnated with an aqueous solution containing 3.6 percentby weight gelatin, 3.6 percent by weight glyoxal, 0.1 percent phosphoricacid and 3.6 percent sorbitol, after which it was dried. The web wasthen subjected to further processing in accordance with Example 1.

The finished web was found to have a basis weight of 25 pounds (24" x36"480 sheets) and to have a thickness of about 0.0038 inch. Porositywas determined to be 222 seconds per 400 cc. of air in a densometertest. Dry tensile strength (average) was found to be 2250 grams per inchand the wet tensile strength 210 grams per inch.

Example 3 One thousand pounds of tobacco leaves and stemmings wereextracted with 1000 pounds of water for two hours at 190 F. in a closedextraction tank. The insoluble portion was separated from the extractand digested together with 600 gallons of water and 6 gallons of 50percent by weight caustic solution for three hours at approximately 260F. and 30 pounds per square inch pressure, after which the pulp wasseparated from the digestion liquor.

The pulpy mass was placed in a conventional paper mill beater togetherwith 1000 gallons of water and refined by brushing for one-half hour,during which time 1500 pounds of activated alumina of less than 200 meshparticle size was added. The slurry thus produced was further refined bypassage through disc refiner and fed to the headbox of a conventionalFourdrinier papermaking machine; and a solution of 2 percent cationicstarch was simultaneously added thereto at a rate of about 5 pounds per450 pounds of tobacco fiber. The headbox consistency was about 0.7percent by weight solids.

The extract of the water-soluble tobacco constituents was evaporated,acidified, and neutralized as in Example 1; and to the neutralizedextract was added 35 pounds of sorbitol and 5 pounds of polyvinylalcohol.

The web produced on the papermaking machine was dried and thenimpregnated thoroughly with the modified extract, and dried again. Thefinished web was found to has basis weight of 59.6 pounds (24" x 36"480sheets) and to contain 60 percent by weight of activated alumina. Thesheet was determined to be 0.0059 inch in thickness, and the porosity(densometer) was 96 seconds per 400 cc. air. The dry tensile strength(average) was 963 grams per inch.

Example 4 Tobacco leaves and water in the proportion of pounds tobaccoto 660 pounds of water were placed in a closed extraction tank togetherwith about 2 percent of potassium hydroxide based on the weight oftobacco. The mixture was heated to F. for three hours, following whichthe extract was separated. The insoluble portion of the tobacco wasplaced in a paper mill beater with water in the proportion of 3 poundstobacco to 360 pounds water and refined for approximately two hours.Titanium dioxide equal to about 6 percent by weight of the tobacco wasadded thereto during the beating operation. The mixture was furtherrefined in a Jordan Machine and screened to remove any large particlesremaining, after which about 6 percent by weight of Karaya gum was addedto the slurry. The slurry thus prepared was fed to the headbox of apapermaking machine, and a slurry of hemp fibers, 5 to 8 mm. in length,was added in a proportion of 1 pound of hemp to 9 pounds of tobacco. Theheadbox consistency was determined at 0.05 percent by weight solids. Theweb produced on the papermaking machine was dried and run through anaqueous dispersion containing 3.6 percent gelatin, 0.5 percent calciumnitrate, 11 percent ethyl alcohol and 0.75 percent formaldehyde, andagain dried.

The extract was evaporated to a specific gravity of about 1.07 andacidified by the addition of a 1:1 mixture of phosphoric and citricacids until a precipitate formed which was separated by filtration anddiscarded. The extract was then neutralized with potassium carbonate andmixed with additional materials to make a solution containing 87.70percent tobacco extract, 1.56 percent gelatin, 0.39 percent dye, 2.35percent glycerin, 7.80 percent ethyl alcohol, and 0.20 percentformaldehyde. The web previously prepared was run through the modifiedextract and dried, following which the web was then run through awater-wax emulsion containing about percent solids and again dried. Theweb was then calendered to form a final tobaccoo web suitable for use asa cigar wrapper material.

The final web was found to have a basis Weight of 26.4 pounds (24" x36"-480 sheets) and to be 0.004 inch in thickness. The porosity(densometer) was determined at 190 seconds per 400 cc. and the drytensile strength (average) was found to be 1966 grams per inch. The wettensile strength (average) was 315 grams per inch.

By the practice of the present invention, there is produced ahomogeneous water-laid tobacco web of thin dimension which contains allthe desirable portions of the original toabcco and which has controlledand uniform characteristics of dimension, color, type of ash,flexibility, strength, taste and aroma. If so desired, the web may bemade milder by removal of acid-insoluble proteins contained in theextract. The web may be made solely of tobacco fibers, or made with anadded minor proportion of natural fibers for additional strength.

By the method of the present invention, large amounts of alumina may beincorporated in a tobacco web for use as a constituent in the tobaccofiller of cigarettes and the like to reduce the burning temperature andthe violatilization of the alkaloids and suspected carcinogens.

The final web may be given the appearance and feel of natural tobacco ofvarying types with the added advantages of improved taste, aroma andburning qualities, and with greater strength and dimensional formsuitable for use on automatic machinery. The web can be tailored withinreasonable limits to meet the specific requirements of the particularend use and may be made at high production speeds with conventionalpapermaking equipment, thus providing a product which is economical toproduce in large quantity. A further advantage of the web material ofthe present invention is that it may be rolled up and storedindefinitely under ordinary storage conditions unlike tobacco webmaterials proposed heretofore which normally require excess moisture andlow temperature storage conditions in order to provide a satisfactoryshelf life.

It will be apparent that variations and modifications will be possiblewithin the skill of the art and all such variations and modificationsare intended to be included within the scope of the invention.

This application is a continuation-in-part of copending applicationSerial No. 775,213 filed November 20, 1958, now abandoned.

We claim:

1. In a method of forming a continuous, thin tobacco web material, thesteps comprising extracting water-soluble constituents from naturaltobacco, forming a web of the insoluble portion of the tobacco,acidifying the extract, neutralizing the acidified extract withpotassium carbonate, and thereafter impregnating the Web with at least aportion of the neutralized extract.

2. The method in accordance with claim 1, wherein a precipitate formedby the acidification of the extract is separated therefrom prior toneutralization with potassium carbonate.

3. In a method of forming a continuous, thin tobacco web material, thesteps comprising extracting water-soluble constituents from naturaltobacco, chemically digesting the insoluble portion of the tobacco toobtain a fibrous pulp, forming a Web with said fibrous tobacco pulp,acidifying the extract, neutralizing the acidified extract withpotassium carbonate, and thereafter impregnating the web with at least aportion of the neutralized extract.

4. In a method of forming a continuous, thin tobacco web material, thesteps comprising extracting water-soluble constituents from naturaltobacco, forming a web of the insoluble portion of the tobacco,impregnating the web with a dilute solution containing aldehyde and across-linkable agent to provide a web having wet-strength, acidifyingthe extract of water-soluble constituents, neutralizing the acidifiedextract with potassium carbonate, and thereafter impregnating the webwith at least a portion of the neutralized extract.

5. The method in accordance with claim 4 wherein a precipitate formed bythe acidification of the extract is separated therefrom prior toneutralization with potassium carbonate.

6. In a method of forming a continuous, thin tobacco web material, thesteps comprising extracting water-soluble constituents from naturaltobacco, chemically digesting the insoluble portion of the tobacco toform a fibrous pulp, forming an aqueous slurry of said fibrous tobaccopulp, forming a thin tobacco web from said aqueous slurry on apapermaking machine, acidifying the extract, neutralizing the acidifiedextract with potassium carbonate, and thereafter impregnating the webwith at least a portion of the neutralized extract.

7. In a method of forming a continuous thin tobacco web material, thesteps comprising extracting water-soluble constituents from naturaltobacco, separating the insoluble portion of the tobacco from theextract, digesting the insoluble portion of the tobacco with a chemicalagent selected from the group consisting of sodium hydroxide and nitricacid to form a fibrous pulp, refining said pulp to form an aqueousslurry of tobacco fibers, feeding said slurry and a solution of cationicmaterial to the headbox of a paper-making machine to form a thin web ofsaid tobacco fibers, removing moisture from the web, acidifying theextract, neutralizing the acidified extract with potassium carbonate,and impregnating said web with at least a portion of the neutralizedextract.

8. In a method of forming a continuous thin tobacco web materialcontaining a substantial amount of activated alumina, the stepscomprising extracting water-soluble constituents from natural tobacco,separating the insoluble portion of the tobacco from the extract,digesting the insoluble portion of the tobacco with a chemical agentselected from the group consisting of sodium hydroxide and nitric acidto form a fibrous pulp, refining said pulp to form an aqueous slurry oftobacco fibers while incorporating therein activated alumina, feedingsaid slurry and a solution of cationic agent to the head box of apaper-making machine to form a thin web of said tobacco fibers, removingmoisture from said web, acidifying the extract, neutralizing theacidified extract with potassium carbonate, impregnating the web with atleast a portion of the neutralized extract, and removing moisture fromthe impregnated web.

9. In a method of forming a continuous thin tobacco Web materialcontaining a substantial amount of activated alumina, the stepscomprising extracting water-soluble constituents from natural tobacco,separating the insoluble portion of the tobacco from the extract,digesting the insoluble portion of the tobacco with a chemical agentselected from the group consisting of sodium hydroxide and nitric acidto form a fibrous pulp, refining said pulp to form an aqueous slurry oftobacco fibers while incorporating therein activated alumina, feedingsaid slurry to the headbox of a paper-making machine to form a thin webof said tobacco fibers, removing moisture from the web, acidifying theextract, neutralizing the acidified extract with potassium carbonate,impregnating the Web with at least a portion of the neutralized extract,and removing moisture from the impregnated web.

10. In a method of forming a continuous thin tobacco web material, thesteps comprising extracting water-soluble constituents of naturaltobacco, separating the insolu ble portion of the tobacco from theextract, digesting the insoluble portion of the tobacco with a chemicalagent selected from the group consisting of sodium hydroxide and nitricacid to form a fibrous pulp, refining said pulp to form an aqueousslurry of tobacco fibers, feeding said slurry to the headbox of apaper-making machine to form a thin web of said tobacco fibers, removingmoisture from the web, acidifying said extract of the water-solubletobacco constituents, neutralizing said acidified extract with potassiumcarbonate, saturating the web with a solution containing a portion ofthe neutralized extract, aldehyde, and a cross-linkable agent selectedfrom the group consisting of protein and polymeric alcohols, removingmoisture from the saturated web, and impregnating the web withneutralized extract.

11. The method of forming a continuous tobacco web material comprisingextracting water-soluble constituents from natural tobacco, separatingthe insoluble portion of the tobacco from the extract, digesting theinsoluble portion of the tobacco with a chemical agent selected from thegroup consisting of sodium hydroxide and nitric acid to form a fibrouspulp, refining said pulp to tobacco fibers, forming a dilute aqueousslurry of tobacco fibers, feeding to the headbox of a paper-makingmachine, said aqueous slurry of tobacco fibers and a dilute slurry ofnatural fibers to provide a dilute headbox slurry containing a majorproportion of tobacco fibers and a minor proportion of conventionalpapermaking fibers, forming a thin web of said tobacco fibers andconventional papermaking fibers, removing moisture from said web,saturating said web with a solution of aldehyde and a cross-linkableagent selected from the group consisting of protein and polymericalcohols, removing moisture from the saturated web, acidifying thewater-soluble portion of the tobacco to a pH of about 4 to 6,neutralizing the acidified extract with potassium carbonate to a pH ofabout 6.5 to 7.2, adding humectant and dye to at least a portion of theneutralized extract, impregnating said web with at least a portion ofthe dye containing extract, removing moisture from the impregnated web,impregnating the web with a water-wax emulsion, and compacting said webunder pressure.

12. The method in accordance with claim 11 wherein a precipitate formedby the acidification of the extract is separated therefrom prior toneutralization with potassium carbonate.

13. The method of forming a continuous tobacco web material comprisingextracting water-soluble constituents from natural tobacco, separatingthe insoluble portion of the tobacco from the extract, digesting theinsoluble portion of the tobacco with a chemical agent selected from thegroup consisting of sodium hydroxide and nitric acid to form a fibrouspulp, refining said pulp to tobacco fibers, forming a dilute aqueousslurry containing a major proportion of tobacco fibers and a minorproportion of conventional papermaking fibers, forming a thin web ofsaid tobacco fibers and conventional papermaking fibers, removingmoisture from said web, acidifying the water-soluble portion of thetobacco to a pH of about 4 to 6, neutralizing the acidified extract withpotassium carbonate to a pH of about 6.5 to 7.2, adding humectant anddye to at least a portion of the neutralized extract, impregnating saidweb with at least a portion of the dye containing extract, removingmoisture from the impregnated web, impregnating the web with a water-waxemulsion, and compacting said web under pressure.

14. The method of forming a continuous tobacco web material comprisingextracting water-soluble constituents from natural tobacco, separatingthe insoluble portion of the tobacco from the extract, digesting theinsoluble portion of the tobacco with a chemical agent selected from thegroup consisting of sodium hydroxide and nitric acid to form a fibrouspulp, refining said pulp and forming a dilute aqueous slurry of tobaccofibers, feeding to the headbox of a papermaking machine said aqueousslurry of tobacco fibers and a solution of cationic agent to form a thinweb of said tobacco fibers, removing moisture from said web, saturatingsaid web with a solution of aldehyde and a cross-linkable agent selectedfrom the group consisting of protein and polymeric alcohols, removingmositure from said saturated web, acidifying the extract, neutralizingthe acidified extract with potassium carbonate, impregnating said webwith at least a portion of the neutralized extract, removing moisturefrom said impregnated Web, impregnating the web with a water-waxemulsion, and compacting said Web under pressure.

15. The method of forming a continuous tobacco web material comprisingextracting water-soluble constituents from natural tobacco, separatingthe insoluble portion of the tobacco from the extract, digesting theinsoluble portion of the tobacco with a chemical agent selected from thegroup consisting of sodium hydroxide and nitric acid to form a fibrouspulp, refining said pulp and forming a dilute aqueous slurry of tobaccofibers, feeding to the headbox of a papermaking machine said aqueousslurry of tobacco fibers and a dilute slurry of natural fibers toprovide a dilute headbox slurry containing a minor proportion ofconventional papermaking fibers, forming a thin web of said tobaccofibers and conventional papermaking fibers, removing moisture from saidweb, saturating said web with a solution of aldehyde and across-linkable agent selected from the group consisting of protein andpolymeric alcohols, removing moisture from said saturated web,acidifying the extract, neutralizing the acidified extract withpotassium carbonate, impregnating said web with at least a portion ofthe neutralized extract, removing moisture from the impregnated web,impregnating the web with a water-wax emulsion, and compacting said webunder pressure.

References Cited in the file of this patent UNITED STATES PATENTS 21,558Durell Sept. 21, 1858 267,764 Wood Nov. 21, 1882 604,338 Rickard May 17,1898 802,487 Wimmer Oct. 24, 1905 1,016,844 Moonelis Feb. 6, 19121,294,310 Sayre et al Feb. 11, 1919 1,338,827 Goodfellow May 4, 19201,599,831 Mackay Sept. 14, 1926 1,631,834 Schorger June 7, 19271,850,139 Richter Mar. 22, 1932 2,007,407 Sadtler July 9, 1935 2,158,565Andrews May 16, 1939 2,207,555 Rowland July 9, 1940 2,483,418 KamletOct. 4, 1949 2,708,175 Samfield et a1. May 10, 1955 2,734,509 Jurgensenet al Feb. 14, 1956 2,734,510 Hungerford et a1 Feb. 14, 1956 2,769,734Bandel Nov. 6, 1956 2,830,596 Frankenburg et al. Apr. 15, 1958 2,845,933Samfield et al Aug. 5, 1958 3,011,921 Specht Dec. 5, 1961 FOREIGNPATENTS 347 Great Britain 1861 10,267 Great Britain 1886 25,830 GreatBritain 1902 OTHER REFERENCES Der Tabak and Die Tababfabrikat, by 1.Wolf, page 53, published 1912 by B. F. Voigt, Leipzig, Germany.

Condensed Chemical Dictionary, 4th Edition, page 148, published 1950 byReinhold Publishing Cor oration.

Organic Chemistry, by E. F. Degering, College Outline Series No. 6, page149, Sixth Edition, published 1951 by Barnes and Noble, New York, NY.

Brill: Technical Association of Pulp and Paper Ind., page 525, vol. 38,No. 9, September 1955 issue.

The Condensed Chemical Dictionary, 5th Ed., page 531, published 1956 byReinhold Publishing Corp., N.Y.

13. THE METHOD OF FORMING A CONTINUOU-S TOBACCO WEB MATERIAL COMPRISINGEXTRACTING WATER-SOLUBLE CONSTITUENTS FROM NATURAL TOBACCO, SEPARATINGTHE INSOLUBLE PORTION OF THE TOBACCO FROM THE EXTRACT, DIGESTING THEINSOLUBLE PORTION OF THE TOBACCO WITH A CHEMICAL AGENT SELECTED FROM THEGROUP CONSISTING OF SODIUM HYDROXIDE AND NITRIC ACID TO FORM A FIBROUSPULP, REFINING SAID PULP TO TOBACCO FIBERS, FORMING A DILUTE AQUEOUSSLURRY CONTAINING A MAJOR PROPORTION OF TOBACCO FIBERS AND A MINORPROPORTION OF CONVENTIONAL PAPERMAKING FIBERS, FORMING A THIN WEB OFSAID TOBACCO FIBERS AND CONVENTIONAL PAPERMAKING FIBERS, REMOVINGMOISTURE FROM SAID WEB, ACIDIFYING THE WATER-SOLUBLE PORTION OF THETOBACCO TO A PH OF ABOUT 4 TO 6, NEUTRALIZING THE ACIDIFIED EXTRACT WITHPOTASSIUM CARBONATE TO A PH OF ABOUT 6.5 TO 7.2, ADDING HUMECTANT ANDDYE TO AT LEAST A PORTION OF THE NEUTRALIZED EXTRACT, IMPREGNATING SAIDWEB WITH AT LEAST A PORTION OF THE DYE CONTAINING EXTRACT, REMOVINGMOISTURE FROM THE IMPREGNATED WEB, IMPREGNATING THE WEB WITH A WATER-WAXEMULSION, AND COMPACTING SAID WEB UNDER PRESSURE.